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GH4 Firmware 2.3, V-log for $99, Epic Panasonic marketing fail
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  • @Vitaliy_Kiselev, I think the thing that is confusing the issue here is that log significantly remaps the actual bit values of the output. In the case of V-Log, the output is clipped at 79IRE, which means that false colour will show 100% clipped pixels as sitting squarely in the upper mids, as will a waveform or histogram display. This cannot be expanded for the purposes of exposure control unless you use a display LUT and meter off the post-LUT values. So, unless you want to record internally at 8-bit AND the GH4 somehow puts a bt.709 LUT on the HDMI output (not sure if it does) you're stuck with the log values coming out the HDMI for preview/metering. To avoid overexposure, you'd need zebras at ~76 IRE, and that's pretty low. False colour would be entirely mis-scaled since most of those expect mids around 50-60 IRE, and the mids in V-Log are about 37-47 IRE, give or take a bit.

    The whole point of LOG is not to put more bits where we think they should be, but to give equal bits per stop of exposure, as befits wide-latitude celluloid film transfer scans. This means, compared to bt. 709 stuff which is what most people are used to, digital log gives actually COMPRESSED midrange in terms of bit-values versus the highlights and shadows. Put another way, since the exposure latitude anticipated by bt. 709 is far less than film you have to put the extra latitude somewhere, and that means taking bits away from the narrower 0-100% reflectance usually catered to by bt.709 and giving them to the extra potential range of the sensor.

    What you end up with is footage where the mids should be sitting at 42 IRE and the highlights WILL clip at 79 IRE, or between 4-5 stops above middle gray. Shadows apparently clip at 7.3 IRE, which is almost 6 linear stops under middle gray, but due to additional compression in the darkest shadows, you are really getting about 7 stops of detail in there.

    If my math is correct, you get approximately 6 IRE per stop of light, which in 8-bit translates to roughly 13 bit-values per stop, or of course four times that in 10-bit.

  • Wouldn't it be simple for Panasonic to add a soft button to toggle a LUT enabled view in the update?

    1. http://www.personal-view.com/talks/discussion/comment/204409#Comment_204409 Last paragraph

    2. what u see is not even close to what you get. Too many people will not be able to correlate between the camera appearing to be able to see into the shadows just fine with perfect noiseless clarity, and the reality that they are grossly underexposed.

  • Switch to FC mode.... good luck with that.

    @shian How about telling me that can be wrong exactly?

    it's gonna be an avalanche of underexposed footage, just like when the GH4 first came out and everybody was setting their profile flat

    Can you explain how it will happen?

  • Switch to FC mode.... good luck with that.

    it's gonna be an avalanche of underexposed footage, just like when the GH4 first came out and everybody was setting their profile flat

  • You have to completely ignore the LCD, or any linear monitor not running a cineon correction LUT. We used to ignore the video assist because it lies. We had to trust the meter.

    I still don not understand, just switch monitor to false color mode, and it must be enough.

    I wonder why you need LUT enabled monitor, as on stage they are used with LOG or raw to show how approximately end result will look. Not for some exposure suggestion. Or I am wrong here?

    You have to have a monitor that can display LUTS to really know what you're shooting, other wise you're just guessing. Even if you're exposed and white balanced correctly it's harder to pull focus with log because the image looks so low contrast.

    Well, idea with LOG is to put as much DR as possible, so it is must be more easy to expose with it, not more hard.

    Follow focus troubles can be real, but adjusting contrast, sharpness and focus assist can be enough.

  • The $500 Blackmagic Video Assist (monitor/recorder) is supposed to be able to toggle back and forth from "film" (log) and "video" display modes. I wonder if that would be an effective way to help monitor exposure on the GH4 while shooting in V-log.

  • @sihian Thanks. Looking forward to see what will be possible.

  • @VK yes the monitor used during shooting. You have to completely ignore the LCD, or any linear monitor not running a cineon correction LUT. We used to ignore the video assist because it lies. We had to trust the meter.

    I have a feeling the in-cam meter will lie to you as well. If @driftwood has it, maybe he can shoot some gray card brackets like these http://www.personal-view.com/talks/discussion/comment/67029#Comment_67029 and show everyone just where everything gets mapped to in terms of exposure.

  • @Vitaly_kiselev You have to have a monitor that can display LUTS to really know what you're shooting, other wise you're just guessing. Even if you're exposed and white balanced correctly it's harder to pull focus with log because the image looks so low contrast.

  • Thanks @shian, I was afraid of not being able to monitor without a LUT, so I'll probably hold off upgrading until I have a better monitor.
    I've shot a lot of s-log using the the F55 and FS7 and am used to having LUT display.
    To piggyback off of what you said I have a feeling we're about to see a lot of poorly exposed and white balanced videos with terrible or no grading.

  • .....It's a different animal. 90% of peeps will have no idea how to use it and will get shitty results... You cannot shoot as if you are still shooting linear video.

    And how you must shoot?

    Without a LUT based monitor to correct the image u will have zero idea what you are getting unless you are proficient with a handheld meter. So either add a monitor that allows you to input LUTs and/or a meter to your pre-order, and then find some instruction on how to use the meter. Or forgo V-log. It's not for you.

    Here you mean monitor used during shooting?

    I also do not fully get obsession with meter here, as by idea with LOG (intended for future grade only) you need to expose highlights as close to 100% as possible (unless you really want some special grade with blown out highlights), and cameras have good tools for it.

  • As soon as I get it on my cam, yeah. Panasonic has not seen fit to give me an advanced copy. I guess my reputation as a volatile voice in terms of how I honestly feel about a product scares manufactures. They don't want me reviewing anything before release, cuz I can't be bought like some of those other "sponsored" cats.

    I'm speaking from my experience with log in general. But as soon as mine arrives and get the chance to play with it, I'll absolutely post the results.

  • @shian Can you post a short scene, correctly shot with V-log and then well corrected? I am really interested to see a result near the optimum.

  • Like I said; re-my nonstop giggling - http://www.personal-view.com/talks/discussion/comment/204357#Comment_204357

    .....It's a different animal. 90% of peeps will have no idea how to use it and will get shitty results... You cannot shoot as if you are still shooting linear video. Without a LUT based monitor to correct the image u will have zero idea what you are getting unless you are proficient with a handheld meter. So either add a monitor that allows you to input LUTs and/or a meter to your pre-order, and then find some instruction on how to use the meter. Or forgo V-log. It's not for you.

    In addition, I love the the way V-log looks on the monitor, it makes me nostalgic for the way film used to get displayed on the old video assist monitors back in the day.

  • Can anyone who has used the v-log update comment on whether it allows you to monitor video using a different color profile in camera while recording v-log to card?

  • I like the Arkterics vid, good looking highlights, color and noise handling.

  • I would like to see a comparason of graded V-log footage compared to proper exposed natural setting. Once in a normal scene and then in an extreme bright/dark scene

  • so correct VK, I'm I the only one not impressed with final image quality from few VLOG tests we seen so far?

  • One thing that is interesting is to see is detailed histograms and banding after grading. As if underexposed (as many samples here), VLOG must be not really much better, but worse.

  • It would be nice to see panasonic make V-log for G7 for 99$

  • got a message from B&H late yesterday after my order. They indicated that the cards would likely ship late Sept (estimated backordered until then). B&H is consistently the best in my dealings.

  • new V Log L footage from our main man Nick Driftwood.